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Post-Wildfire Phenology: Biogeomorphic Implications for the Great Basin: Joel Sankey


Project Title: Post-Wildfire Phenology: Biogeomorphic Implications for the Great Basin
Mendenhall Fellow: Joel Sankey, (520) 670-6671, ext. 232jsankey@usgs.gov
Duty Station: Tucson, AZ
Start Date: January 18, 2011
Education: Ph.D. Engineering and Applied Science—Geoscience, Idaho State University
Research Advisors: Cynthia Wallace, (520) 670-5589, cwallace@usgs.gov; Jake Weltzin, (520) 626-3821, jweltzin@usgs.gov
  Joel Sankey

Project Description: The purpose of this research is to understand the effects of increased length of the annual wildfire season on the post-fire phenology of herbaceous vegetation, which drives the potential for increased wind erosion of soil in semiarid rangelands of the Great Basin, USA. Through this project we are linking an existing long-term database of post-fire vegetation recovery for Great Basin shrub-steppe landscapes developed by U.S. Geological Survey scientists with land surface phenology measurements made with archived, long-term MODIS and AVHRR satellite data. An increase in wildfire frequency and an increase in the length of the annual wildfire season are two of the most prominent effects of climate change in the western United States. Increase in wildfire frequency is expected to increase wind erosion of soil. Effects of increased length of the annual fire season on the current wind erosion regime are unknown, however, particularly in more northern landscapes such as the Great Basin desert that experience a strong seasonality in annual climate, with relatively cold, snowy winters, hot dry summers, and often wetter spring and fall seasons. When wildfires burn in the summer, there is the paradigm that green-up of herbaceous vegetation generally occurs in the subsequent spring after the winter dormant season in the Great Basin. An increase in the propensity for early spring or late fall wildfires might result in an insignificant increase in wind erosion, if post-fire green-up of herbaceous vegetation occurs relatively rapidly (for example, prior to the winter dormant season). Conversely, surfaces might be prone to erosion over a much longer time period if herbaceous vegetation is slow to recover following wildfire. In such instances, green-up might not occur until spring of the subsequent year’s growing season. Furthermore, herbaceous vegetation might re-establish at extremely low and variable levels of cover for multiple years before exhibiting a degree of protection suitable to limit wind erosion. Finally, expensive post-fire seeding treatments are commonly conducted to promote the establishment of a desirable vegetation community, but the effectiveness of these treatments for stabilizing the soil surface are not well understood.

Specific research questions being addressed are:

    1. For how long after fire do burned areas remain significant dust sources?
    2. Do seeding treatments increase rates of soil stabilization?
    3. What will be the impact of the increased length of the wildfire season that is occurring with climate change? For example:
      1. Will more early season fires result in longer periods of enhanced wind erosion potential?
      2. Will more late season fires result in shorter periods of enhanced wind erosion potential?
      3. Does post-fire green-up (soil stabilization) vary with fire date?
Graph showing period of soil destablization and enhanced erosion

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Last modified: 16:08:32 Thu 13 Dec 2012